Chemical resistant lead-free glass frit compositions

ABSTRACT

Glass frit compositions for use in glazes or enamels have a fiber softening point of 535° C. or more and are free of cadmium, lead and arsenic and consist essentially of Bi 2  O 3  --B 2  O 3  --SiO 2  with R 2  O being 2-8% and RO being 0-9% by weight.

The present invention relates to glass frit compositions that are free of lead, arsenic and cadmium and have good chemical resistance.

BACKGROUND OF THE INVENTION

The present invention relates to lead-free, arsenic-free and cadmium-free glass frit compositions for use in glazing, enameling and for decorating food service ware such as glass tumblers and chinaware. The compositions have increased chemical resistance, especially acid resistance over glass frit compositions of U.S. Pat. No. 4,446,241 issued May 1, 1984 for an invention of Francel, Horn and Stewart, and assigned to the same assignee as the present invention. This patent is incorporated by reference, the patent disclosing and defining properties of the compositions including the fiber softening point, the coefficient of thermal expansion and the chemical resistance such as the alkali resistance and the acid resistance. As therein stated, the acid resistance is measured by a standard test using 4% by weight acetic acid and exposing the samples thereto for 24 hours at room temperature. As also stated therein, the alkali resistance test is made using 9% sodium pyrophosphate at 60° C. for 8 hours.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a glass frit composition that is free of lead, arsenic and cadmium, the composition having increased chemical resistance including an acid resistance in which the weight percent loss is below about 0.9.

It is an object of the present invention to provide a glass frit composition having increased acid resistance including a weight loss percent of less than about 0.9 in the standard acid test using 4% by weight acetic acid, the composition consisting essentially of Bi₂ O₃ --B₂ O₃ --SiO₂ with the amount of R₂ O being about 2-8% by weight and RO being about 0-9% by weight.

These and other objects will be apparent from the description that follows and the depending claims.

THE INVENTION

The present invention provides a glass frit composition that is free of lead and arsenic, the composition having a fiber softening point of at least about 535° C. the composition having good chemical resistance and consisting essentially of the following components in parts by weight:

    ______________________________________                                         COMPONENT       PARTS                                                          ______________________________________                                         Bi.sub.2 O.sub.3                                                                               48-57                                                          SiO.sub.2       29-38                                                          B.sub.2 O.sub.3 3-8                                                            R.sub.2 O       2-8                                                            TiO.sub.2       0-2                                                            ZrO.sub.2       0-8                                                            Al.sub.2 O.sub.3                                                                               0-2                                                            BaO             0-4                                                            ZnO             0-3                                                            CaO             0-9                                                            ______________________________________                                    

wherein RO is 0-about 9, R₂ O₃ is about 57-64, and RO₂ is about 32-39, the alkali resistance in weight % loss being below about 0.9 and the acid resistance in weight % loss being below about 0.9.

The preferred ranges of the ingredients are as follows:

    ______________________________________                                         INGREDIENTS   PARTS BY WEIGHT                                                  ______________________________________                                         Bi.sub.2 O.sub.3                                                                             50-56                                                            SiO.sub.2     30-34                                                            B.sub.2 O.sub.3                                                                              4-5                                                              R.sub.2 O     2-5                                                              TiO.sub.2     0-2                                                              ZrO.sub.2     0-3                                                              Al.sub.2 O.sub.3                                                                             0-2                                                              RO            0-7                                                              F             0-1/2                                                            R.sub.2 O.sub.3                                                                              58-62                                                            RO.sub.2      32-37                                                            ______________________________________                                    

R₂ O is an alkali metal oxide such as Na₂ O, K₂ O and Li₂ O with Na₂ O and K₂ O generally being at least 50% by weight of the R₂ O component. RO is an alkaline earth oxide such as CaO, or ZnO or BaO with CaO generally being present in greater amounts than the others in the RO component.

The improved acid resistance of the frit composition of the present invention is generally high with losses less than about 0.9% by weight and often, preferably, is about 0.7 to 0.75% by weight or below as seen in many of the working examples that follow. The alkali resistance is generally less than about 0.9% by weight and preferably about 0.7 or 0.8% by weight or less.

Following procedures known in the art and as set forth in the previously mentioned U.S. Pat. No. 4,446,241 to Francel et al, raw batch compositions were mixed, melted, fritted and tested to provide the following working examples in which the ingredients are given in parts by weight.

    ______________________________________                                         INGREDIENT 1         2      3      4    5                                      ______________________________________                                         Bi.sub.2 O.sub.3                                                                          50        57     56     50   50                                     SiO.sub.2  29        29     34     29   29                                     TiO.sub.2  2         2      2      0    2                                      ZrO.sub.2  3         3      0      3    3                                      B.sub.2 O.sub.3                                                                           5         5      3      5    5                                      Al.sub.2 O.sub.3                                                                          2         2      0      2    2                                      BaO        4         0      0      0    0                                      ZnO        3         0      0      0    0                                      CaO        0         0      0      9    7                                      Li.sub.2 O 2         0      0      2    2                                      K.sub.2 O  0         2      2      0    0                                      Na.sub.2 O 0         0      3      0    0                                      R.sub.2 O  2         2      5      2    2                                      RO         7         0      0      9    7                                      R.sub.2 O.sub.3                                                                           57        64     59     57   57                                     RO.sub.2   34        34     36     32   34                                     Weight & Losses                                                                Alkalies   0.3       0.23   0.24   0.00 0.60                                   Acid       0.5       0.60   0.46   0.34 0.43                                   ______________________________________                                                   6        7       8      9     10                                     ______________________________________                                         Bi.sub.2 O.sub.3                                                                         50       50      50     50    50                                     SiO.sub. 2                                                                               32       33      38     37    37                                     B.sub.2 O.sub.3                                                                          7        7       7      5     8                                      Li.sub.2 O                                                                               0        0       0      0     0                                      Na.sub.2 O                                                                               5        7       5      8     5                                      K.sub.2 O                                                                      R.sub.2 O 5        7       5      8     5                                      TiO.sub.2                                                                      ZrO.sub.2 5        3       0      0     0                                      Al.sub.2 O.sub.3                                                               BaO                                                                            ZnO                                                                            CaO       1        0       0                                                   R.sub.2 O.sub.3                                                                          57       57      57     55    58                                     RO.sub.2  37       36      38     37    37                                               Loss     Loss    Loss   Loss  Loss                                   Alkalies  0.45     0.50    0.82   0.56  0.00                                   Acid      0.87     0.85    0.13   0.38  0.00                                   F.S.P.°C.                                                                         619      591     581    582   580                                    ______________________________________                                                   11      12         13    14                                          ______________________________________                                         Bi.sub.2 O.sub.3                                                                         53      51         50    48                                          SiO.sub.2 32      31         31    31                                          B.sub.2 O.sub.3                                                                          7       7          7     8                                           Li.sub.2 O                                                                               0       0                                                            Na.sub.2 O                                                                               5       5          5     5                                           K.sub.2 O                                                                      R.sub.2 O 5       5          5     5                                           TiO.sub.2                                                                      ZrO.sub.2 3       6          6     8                                           Al.sub.2 O.sub.3                                                               BaO                                                                            ZnO                                                                            CaO                                                                            F         1       0                                                            R.sub.2 O.sub.3                                                                RO.sub.2                                                                                 Loss    Gain       Gain  Loss                                        Alkalies  0.0     +0.45      +0.29 0.61                                        Acids     0.0     +0.42      +0.26 0.64                                        F.S.P.°C.                                                                         572     594        569   598                                         ______________________________________                                    

It can be seen from the working examples that substantial amounts of Bi₂ O₃ in the Bi₂ O₃ --B₂ O₃ --SiO₂ glass system provide many advantages including excellent acid resistance that is generally higher with lower losses than the acid resistance of the glass frit compositions of the Francel et al U.S. Pat. No. 4,446,241.

These compositions are resistant to acids, detergents and alkalies which makes them applicable to different substrates exposed to fruit juices, foods, and high alkali detergents. These compositions retain their gloss after exposure to acetic acid (4%) and citric acid (10%). Their weight losses were below 0.9% of the original weight of the fired coating.

Tests in alkali detergents were conducted with these compositions with resultant low losses. The compositions can be fired at and above 590° C. (1100° F.) on variety of substrates--glasses, oxides, and metals. The compositions of the present invention have fiber softening points of at least about 535° C., the range being from about 535° to 609° C. or more, up to about 619° or 625° C. 

What is claimed is:
 1. A glass frit composition that is free of lead, cadmium and arsenic, the composition having a fiber softening point of at least about 535° C., the composition having good chemical resistance and consisting essentially of the following components in parts by weight per 100:

    ______________________________________                                         COMPONENT       PARTS                                                          ______________________________________                                         Bi.sub.2 O.sub.3                                                                               48-57                                                          SiO.sub.2       29-38                                                          B.sub.2 O.sub.3 3-8                                                            R.sub.2 O       2-8                                                            TiO.sub.2       0-2                                                            ZrO.sub.2       0-8                                                            Al.sub.2 O.sub.3                                                                               0-2                                                            BaO             0-4                                                            ZnO             0-3                                                            CaO             0-9                                                            ______________________________________                                    

wherein RO is 0-about 9, R₂ O₃ is about 57-64, and RO₂ is about 32-39, the alkali resistance in weight % loss being below about 0.9, measured using 9% sodium pyrophosphate at 60° C. for 8 hours, and the acid resistance in weight % loss being below about 0.9, measured using 4% by weight acetic acid for 24 hours at room temperature, RO being at least one of BaO, CaO or ZnO, and R₂ O being an alkali metal oxide.
 2. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 50                                                            SiO.sub.2        29                                                            TiO.sub.2        2                                                             ZrO.sub.2        3                                                             B.sub.2 O.sub.3  5                                                             Al.sub.2 O.sub.3 2                                                             BaO              4                                                             ZnO              3                                                             CaO              0                                                             Li.sub.2 O       2                                                             K.sub.2 O        0                                                             Na.sub.2 O       0                                                             R.sub.2 O        2                                                             RO               7                                                             R.sub.2 O.sub.3  57                                                            RO.sub.2         34                                                            Weight % Losses                                                                Alkalies         0.3                                                           Acid             0.5 .                                                         ______________________________________                                    


3. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 57                                                            SiO.sub.2        29                                                            TiO.sub.2        2                                                             ZrO.sub.2        3                                                             B.sub.2 O.sub.3  5                                                             Al.sub.2 O.sub.3 2                                                             BaO              0                                                             ZnO              0                                                             CaO              0                                                             Li.sub.2 O       0                                                             K.sub.2 O        2                                                             Na.sub.2 O       0                                                             R.sub.2 O        2                                                             RO               0                                                             R.sub.2 O.sub.3  64                                                            RO.sub.2         34                                                            Weight % Losses                                                                Alkalies         0.23                                                          Acid             0.60 .                                                        ______________________________________                                    


4. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 56                                                            SiO.sub.2        34                                                            TiO.sub.2        2                                                             ZrO.sub.2        0                                                             B.sub.2 O.sub.3  3                                                             Al.sub.2 O.sub.3 0                                                             BaO              0                                                             ZnO              0                                                             CaO              0                                                             Li.sub.2 O       0                                                             K.sub.2 O        2                                                             Na.sub.2 O       3                                                             R.sub.2 O        5                                                             RO               0                                                             R.sub.2 O.sub.3  59                                                            RO.sub.2         36                                                            Weight % Losses                                                                Alkalies         0.23                                                          Acid             0.60 .                                                        ______________________________________                                    


5. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 50                                                            SiO.sub. 2       29                                                            TiO.sub.2        0                                                             ZrO.sub.2        3                                                             B.sub.2 O.sub.3  5                                                             Al.sub.2 O.sub.3 2                                                             BaO              0                                                             ZnO              0                                                             CaO              9                                                             Li.sub.2 O       2                                                             K.sub.2 O        0                                                             Na.sub.2 O       0                                                             R.sub.2 O        2                                                             RO               9                                                             R.sub.2 O.sub.3  57                                                            RO.sub.2         32                                                            Weights % Losses                                                               Alkalies         0.00                                                          Acid             0.34 .                                                        ______________________________________                                    


6. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 50                                                            SiO.sub.2        29                                                            TiO.sub.2        2                                                             ZrO.sub.2        3                                                             B.sub.2 O.sub.3  5                                                             Al.sub.2 O.sub.3 2                                                             BaO              0                                                             ZnO              0                                                             CaO              7                                                             Li.sub.2 O       2                                                             K.sub.2 O        0                                                             Na.sub.2 O       0                                                             R.sub.2 O        2                                                             RO               7                                                             R.sub.2 O.sub.3  57                                                            RO.sub.2         34                                                            Weight % Losses                                                                Alkalies         0.60                                                          Acid             0.43 .                                                        ______________________________________                                    


7. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 50                                                            SiO.sub.2        32                                                            B.sub.2 O.sub.3  7                                                             Li.sub.2 O       0                                                             Na.sub.2 O       5                                                             K.sub.2 O        0                                                             R.sub.2 O        5                                                             TiO.sub.2        0                                                             ZrO.sub.2        5                                                             Al.sub.2 O.sub.3 0                                                             BaO              0                                                             ZnO              0                                                             CaO              1                                                             F                0                                                             R.sub.2 O.sub.3  57                                                            RO.sub.2         37                                                            Weight % Losses                                                                Alkalies         0.45                                                          Acid             0.87 .                                                        ______________________________________                                    


8. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 50                                                            SiO.sub.2        37                                                            B.sub.2 O.sub.3  8                                                             Li.sub.2 O       0                                                             Na.sub.2 O       5                                                             K.sub.2 O        0                                                             R.sub.2 O        5                                                             TiO.sub.2        0                                                             ZrO.sub.2        0                                                             Al.sub.2 O.sub.3 0                                                             BaO              0                                                             ZnO              0                                                             CaO              0                                                             F                0                                                             R.sub.2 O.sub.3  58                                                            RO.sub.2         37                                                            Weight % Losses                                                                Alkalies         0.00                                                          Acid             0.00 .                                                        ______________________________________                                    


9. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 51                                                            SiO.sub.2        31                                                            B.sub.2 O.sub.3  7                                                             Li.sub.2 O       0                                                             Na.sub.2 O       5                                                             K.sub.2 O        0                                                             R.sub.2 O        5                                                             TiO.sub.2        0                                                             ZrO.sub.2        6                                                             Al.sub.2 O.sub.3 0                                                             BaO              0                                                             ZnO              0                                                             CaO              0                                                             F                0                                                             R.sub.2 O.sub.3  58                                                            RO.sub.2         37                                                            Weight % Losses                                                                Alkalies         +0.45                                                         Acid             +0.42 .                                                       ______________________________________                                    


10. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 50                                                            SiO.sub.2        31                                                            B.sub.2 O.sub.3  7                                                             Li.sub.2 O       0                                                             Na.sub.2 O       5                                                             K.sub.2 O        0                                                             R.sub.2 O        5                                                             TiO.sub.2        0                                                             ZrO.sub.2        6                                                             Al.sub.2 O.sub.3 0                                                             BaO              0                                                             ZnO              0                                                             CaO              0                                                             F                0                                                             R.sub.2 O.sub.3  57                                                            RO.sub.2         37                                                            Weight % Losses                                                                Alkalies         +0.29                                                         Acid             +0.26 .                                                       ______________________________________                                    


11. A composition as defined in claim 1 in which the composition is as follows:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 48                                                            SiO.sub.2        31                                                            B.sub.2 O.sub.3  8                                                             Li.sub.2 O       0                                                             Na.sub.2 O       5                                                             K.sub.2 O        0                                                             R.sub.2 O        5                                                             TiO.sub.2        0                                                             ZrO.sub.2        8                                                             Al.sub.2 O.sub.3 0                                                             BaO              0                                                             ZnO              0                                                             CaO              0                                                             F                0                                                             R.sub.2 O.sub.3  56                                                            RO.sub.2         39                                                            Weight % Losses                                                                Alkalies         0.61                                                          Acid             0.64 .                                                        ______________________________________                                    


12. A glass frit composition that is free of lead, cadmium and arsenic, the composition having a fiber softening point of at least about 535° C., the composition having excellent chemical resistance and consisting essentially of the following components in approximate parts by weight per 100:

    ______________________________________                                         COMPONENTS       PARTS                                                         ______________________________________                                         Bi.sub.2 O.sub.3 50-56                                                         SiO.sub.2        30-34                                                         B.sub.2 O.sub.3  4-5                                                           R.sub.2 O        2-5                                                           TiO.sub.2        0-2                                                           ZrO.sub.2        0-3                                                           Al.sub.2 O.sub.3 0-2                                                           RO               0-7                                                           F                0-1/2                                                         R.sub.2 O.sub.3  58-62                                                         RO.sub.2          32-37,                                                       ______________________________________                                    

the alkali resistance in weight % loss no more than about 0.8, measured using 9% sodium pyrophosphate at 60°C. for 8 hours, and the acid resistance in weight % loss being no more than about 0.75, measured using 4% by weight acetic acid for 24 hours at room temperature, at least one of BaO, CaO or ZnO, and R₂ O being an alkali metal oxide. 